Interfacial effects and microstructure development in the PP/PP-g-MA/ diamine-modified nanoclay nanocomposite

The aim of the work reported in this Letter was to enhance the interfacial interaction between the modified nanoclay and polymer matrix by surface modification of montmmorilonite (MMT) with 1,12 diaminododecane (DA) via cation exchange reaction. The diamine-modified nanoclay was utilised to prepare a polypropylene-based nanocomposite sample and its performance was compared with the nanocomposite sample containing Cloisite^®20A. The nanocomposite samples were prepared by melt compounding process in a laboratory internal mixer. The results of X-ray diffraction in combination with Fourier transform infrared (FTIR) analysis confirmed the cation exchange reaction. The FTIR analysis performed on the DA containing the nanocomposite sample also evidenced that the chemical reaction between the amine groups of the MMT surface modifier and the maleic group of the compatibiliser has occurred. However, only a little increase in nanoclay interlayer d-spacing was observed. The melt linear viscoelastic results of this sample showed a considerable increased complex viscosity, η*, and storage modulus, G´, in the whole range of frequency, but did not show a low frequency solid body behaviour similar to that exhibited by the Cloisite´20A containing sample. The extent of enhancement of interfacial interaction between the silicate layer and the polymer matrix chains in the DA containing sample led to increase of the heat of fusion and crystallisation temperature (T_C). From these results, a special microstructure consisting of individual nanoclay aggregates, which were observed in the transmission electron microscopy micrograph, with strong interfacial adhesion to the matrix, is proposed for the DA containing nanocomposite sample.